The bottom left looks pretty well tied down, but what about the edge away from your camera, and what looks like a possibly noisy section pointing off to the top right?

Is any part of it at all shiny, or anything it might be hitting showing impact marks?
That MAY not be the culprit, in that if you hit it, it will rattle.. can you move it at all anywhere such that it hits anything else?
If so, you might be able to tame the noise by bolting a small hunk of inert metal to it where it flexes [I wouldn't suggest lead]... but I'd also keep looking.

Thanks for the TSB. Doesn't apply to my model year (2011) and my bolts are present and tight. Nice to know that it is not completely an isolated case.

Doesn't seem be hitting anything. The noise sounds like a loose license plate, which when you tap on this shield makes the same noise (it kind of is like a tuning fork in it takes very little force to replicate the noise). It is tightly secured, but there is nothing for it to connect to at the top end (top right of photo). Just the bends of the metal to provide the support from the base where it is screwed down.

Doesn't do it on "normal" bumps but I have some rough roads near my house that seem to cause just the right vibration.

Thanks for the TSB. Doesn't apply to my model year (2011) and my bolts are present and tight. Nice to know that it is not completely an isolated case.

Doesn't seem be hitting anything. The noise sounds like a loose license plate, which when you tap on this shield makes the same noise (it kind of is like a tuning fork in it takes very little force to replicate the noise). It is tightly secured, but there is nothing for it to connect to at the top end (top right of photo). Just the bends of the metal to provide the support from the base where it is screwed down.

Doesn't do it on "normal" bumps but I have some rough roads near my house that seem to cause just the right vibration.

Can you get at it enough to pop rivet or screw a small hunk of stiffener to it?
A bit of cast iron would be good, as it tends not to resonate much, but I'd suspect just about any bit of heavier metal would work to shut it up.

Can you get at it enough to pop rivet or screw a small hunk of stiffener to it?
A bit of cast iron would be good, as it tends not to resonate much, but I'd suspect just about any bit of heavier metal would work to shut it up.

... a louder stereo could also work.

I like the rivet or stiffener idea. Even just adding something like caulk (I know it has to be able to handle exhaust temperature to prevent a fire) would end the tuning fork effect.

.. Louder stereo has worked, plus once winter comes the windows will be up .